Optical communication devices are known, each of which includes a core composed of a silicon material, and an optical waveguide containing silicon oxide and covering the core (refer to Japanese Laid-open Patent Application No. 2011-27769, for example). Referring to FIG. 1, an optical communication device includes an optical waveguide 91 adapted to propagate light to an external optical device, a coupler 92 adapted to split the light incoming from the optical waveguide 91, an optical waveguide 93 adapted to guide the light split by the coupler 92, and a detector 94 adapted to detect the intensity of the light guided through the optical waveguide 93, for example.
In the optical waveguide including the core composed of the silicon material, the index of refraction of light varies between silicon contained in the core and the silicon oxide contained in cladding. This provides a strong confinement of light, often resulting in scattering of the light on the wall surface of the core. Such scattering of light may increase an optical loss due to scattering per unit length of the optical waveguide (known as scattering loss).
Accordingly, such an increased optical loss in the optical waveguide 93 requires a sufficient amount of split light that is split at the coupler 92 (to the detector 94).